• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.75-82
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• 2003

We can foresee the rapidly growing of users by development of VoIP service what can transmit a audio traffic with low cost among a lots application using internet. VoIP needs a standardized protocol that is able to do signaling for offering high quality of services such as mobility, universal number, multiparty conference, voice mail, automatic call distribution. At the present time, a base composition elements of SIP(Session Intiation Protocol) are developing for offering VoIP based SIP in the inside and outside of the country, because SIP of IETF which has a strength from 'fast connection', 'parsing' & 'easy to compile' points of view. This paper suggests a type of Hybrid SIP Server for providing some services as 'a reducing load of SIP server that process a request method from users', 'efficiency of managing networks', 'offering services to many users'.

• Journal of Sensor Science and Technology
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• v.22 no.1
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• pp.18-27
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• 2013

Real-time monitoring is one of the prime necessities in a weapon flight test that is required for the efficient and timely collection of large amounts of high-rate sampled data acquired by an event-trigger. The wireless sensor network is a good candidate to resolve this requirement, especially considering the inhospitable environment of a weapon flight test. In this paper, we propose a priority based multi-channel MAC protocol with CSMA/CA over a single radio for a real-time monitoring of a weapon flight test. Multi-channel transmissions of nodes can improve the network performance in wireless sensor networks. Our proposed MAC protocol has two operation modes: Normal mode and Priority Mode. In the normal mode, the node exploits the normal CSMA/CA mechanism. In the priority mode, the node has one of three grades - Class A, B, and C. The node uses a different CSMA/CA mechanism according to its grade that is determined by a signal level. High grade nodes can exploit more channels and lower backoff exponents than low ones, which allow high grade nodes to obtain more transmission opportunities. In addition, it can guarantee successful transmission of important data generated by high grade nodes. Simulation results show that the proposed MAC exhibits excellent performance in an event-triggered real-time application.

• The Transactions of the Korea Information Processing Society
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• v.4 no.1
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• pp.195-208
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• 1997

ISDN is network which has been developed to integrate and transfer some information(data, video, voice). In the ISDN, security problem that threat and intrusion about important information resource increase because every information is transferred in the form of digital and access of network has patiency. In this paper, for protect important information resource, studied that apply application method and encryption system to ISDN, and system structure, ITU-T Q.931 protocol were analyzed, and proposable encryption key distribution protocol, call control with hybrid encryption system for user information privacy to provide security service.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.10
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• pp.3361-3377
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• 2014

Synchronous computing models provided by real-time synchrony protocols, such as TTA [1] and PALS [2], greatly simplify the design, implementation, and verification of real-time distributed systems. However, their application to real systems has been limited since their assumptions on underlying systems are hard to satisfy. In particular, most previous real-time synchrony protocols hypothesize the existence of underlying fault tolerant real-time networks. This, however, might not be true in most soft real-time applications. In this paper, we propose a practical approach to a synchrony protocol, called Quality-Aware PALS (qPALS), which provides the benefits of a synchronous computing model in environments where no fault-tolerant real-time network is available. qPALS supports two flexible global synchronization protocols: one tailored for the performance and the other for the correctness of synchronization. Hence, applications can make a negotiation flexibly between performance and correctness. In qPALS, the Quality-of-Service (QoS) on synchronization and consistency is specified in a probabilistic manner, and the specified QoS is supported under dynamic and unpredictable network environments via a control-theoretic approach. Our simulation results show that qPALS supports highly reliable synchronization for critical events while still supporting the efficiency and performance even when the underlying network is not stable.

• The Journal of the Korea Contents Association
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• v.1 no.1
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• pp.109-117
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• 2001

The WAP gateway. for wireless internet applications services, is a software that is placed between the user terminals(PDA, mobile phones) and the WAP/Web server. H is a middleware system that converts the protocol of a packet network to the protocol on the WAP network, and supports the encoding of WML documents. In this paper, we designed and implemented the WAP gateway based on the WAP specification version 1.2 announced by the WAP forum. It provides cross-platform compatibility by being implemented by the Java language. Compared with a Kannel system using a Nokia tool kit version 1.2, it provides a more excellent performance and a stability.

• The Transactions of the Korea Information Processing Society
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• v.4 no.5
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• pp.1327-1336
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• 1997

Test generation from the communication protocol specified in I/OFSM protocol is based on the asumption that the specification S and implemenataiton I are storngly, connected,minmal and deterministic.In this paper,we identify why these asumptions are necessary for minimal test cases genration from I/OFSM protocol speci-fication,and we propose a graph Rewriting System and its application to the specification I/OFSM for verifying its storng cinnectivity.We prove that the suggested algorithm is more dffcient thah the traditional strongly connected compoment find algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1C
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• pp.93-101
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• 2006

Proxy signature schemes based on delegation of warrant are frequently studied in these days. Proxy signature schemes that used in these days have some problems about the security. Especially, it is difficult to prevent misuse of certification and private key. In this thesis, we propose the more stronger security structure by turning the point from original signer with proxy signer to original signer with verifier, and the proposed protocol is more stronger than previous scheme and can be applied to various PKI based application.

• ETRI Journal
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• v.28 no.4
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• pp.411-424
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• 2006

This paper presents a multimedia streaming platform for efficiently transmitting MPEG-4 content over IP networks. The platform includes an MPEG-4 compliant streaming server and client, supporting object-based representation of multimedia scenes, interactivity, and advanced encoding profiles defined by the ISO standard. For scalability purposes, we employ an application-layer multicast scheme for media transmission using overlay networks. The overlay network, governed by the central entity of the network distribution manager, is dynamically deployed according to a set of pre-defined criteria. The overlay network supports both broadcast delivery and video-on-demand content. The multimedia streaming platform is standards-compliant and utilizes widespread multimedia protocols such as MPEG-4, real-time transport protocol, real-time transport control protocol, and real-time streaming protocol. The design of the overlay network was architected with the goal of transparency to both the streaming server and the client. As a result, many commercial implementations that use industry-standard protocols can be plugged into the architecture relatively painlessly and can enjoy the benefits of the platform.

• ETRI Journal
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• v.29 no.6
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• pp.755-768
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• 2007

A very promising application of active RFID systems is the electronic seal, an electronic device to guarantee the authenticity and integrity of freight containers. To provide freight containers with a high level of tamper resistance, the security of electronic seals must be ensured. In this paper, we present the design and implementation of an electronic seal protection system. First, we propose the eSeal Protection Protocol (ePP). Next, we implement and evaluate various cryptographic primitives as building blocks for our protocol. Our experimental results show that AES-CBC-MAC achieves the best performance among various schemes for message authentication and session key derivation. Finally, we implement a new electronic seal system equipped with ePP, and evaluate its performance using a real-world platform. Our evaluation shows that ePP guarantees a sufficient performance over an ARM9-based interrogator.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.362-367
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• 2005

Control network adopted in the national power-plant or manufactory are mostly vendor-dependent products, which have their own special specification, components and individual communication methods. These systems not only raise installation cost, but also bring many difficulties to maintenance and extension. To overcome these problems, this paper introduces a development and application case of a new "PC/Ethernet-based fieldbus" architecture and protocol to be used in mid-level fieldbus. The designed system has a basic idea of "3 Layers fieldbus over Standard-LAN" and implemented on PCs. PC gives user friendly environment. By using an open standard Ethernet in layer 1,2, the system has low cost, wide communication bandwidth and high compatibility. Layer 3 protocol designed for large realtime data communication makes user bypass TCP/IP layer and gives user direct access to the Ethernet. This new protocol eliminates potential collision of Ethernet, and transmits large periodic/non-periodic control data by using long-frame/wide-bandwidth of Ethernet effectively, and offers simple API-Services to the upper layer. Since the system have installed in H-power plant simulator and U-nuclear power plant simulator in Korea, it have been proved to be efficient and stable without any trouble in realtime communication service for full-scope plant simulator that has a lot of control elements.